Sample records for selenium 65
from WorldWideScience.org

Sample records 1 - 2 shown.



1

Determinação direta de selênio em água de coco e em leite de coco utilizando espectrometria de absorção atômica com atomização eletrotérmica em forno de grafite/ Direct determination of selenium in coconut water and coconut milk using graphite furnace atomic absorption spectrometry

Aleixo, Poliana C.; Nóbrega, Joaquim A.; Santos Júnior, Dário; Muller, Regina C. S.
2000-06-01

Resumo em inglês Selenium is both essential and toxic to man and animals, depending on the concentration and the ingested form. Most fruits and vegetables are poor sources of selenium, but coconut can be a good selenium source. Samples were suspended (1 + 4 v/v) in a mixture of tertiary amines soluble in water (10% v/v CFA-C). This simple sample treatment avoided contamination and decreased the analysis time. The standard additions method was adopted for quantification. The action of the (mais) autosampler was improved by the presence of the amines mixture in the suspension. A Varian model AA-800 atomic absorption spectrometer equipped with a graphite furnace and a GTA 100 autosampler was used for selenium determination in coconut water and coconut milk. Background correction was performed by means of the Zeeman effect. Pyrolytically coated graphite tubes were employed. Using Pd as chemical modifier, the pyrolysis and the atomization temperatures were set at 1400 and 2200ºC, respectively. For six samples, the selenium concentration in coconut water varied from 6.5 to 21.0 mug L-1 and in coconut milk from 24.2 to 25.1 mug L-1. The accuracy of the proposed method was evaluated by an addition-recovery experiment and all recovered values are in the 99.5-102.3% range. The main advantage of the proposed method is that it can be directly applied without sample decomposition.

Scientific Electronic Library Online (Portuguese)

2

Carcinoma da próstata e envelhecimento: aspectos preocupantes/ Prostate cancer and aging

Pina, Francisco Madeira; Lunet, Nuno; Dias, Manuel Macedo
2006-09-01

Resumo em português O envelhecimento cursa com adaptações de hormonas, citocinas, e factores de crescimento progressivas, umas com função provavelmente protectora, outras ligadas ao aumento de risco de morte por causas cardiovasculares e neoplásicas. Relativamente às terapêuticas androgénicas de substituição no idoso, em utilização crescente e prolongada, mantem se a dúvida sobre o impacto no risco de desenvolvimento do cancro da próstata. A nossa experiência em casos incident (mais) es de cancro da próstata demonstra que, à medida que a idade avança, sobe também a proporção de doentes com cancros da próstata com piores factores de prognóstico de recidiva/progressão (PSA basal mais elevado, risco de metastização óssea, tumores com pior diferenciação histológica). Enquanto que a prevenção primária quimio-endócrina aguarda resultados de vários estudos em curso (nomeadamente com inibidores da 5 α-reductase, selιnio e vitamina E) para se afirmar, a prevenção secundária, baseada em resultados parciais de grandes estudos internacionais e na expansão das medidas básicas do diagnóstico precoce (exame digital rectal e PSA), avança com a generalização das terapêuticas radicais. A nossa experiência de 15 anos de prostatectomia radical revela que os indivíduos idosos (> 65 anos) representam metade dos candidatos, nos quais se observa uma maior proporção de indivíduos com tumores com Gleason ≥ 7, e maior proporção de indivíduos classificados em grupos de maior risco de recidiva/progressão. As diferentes formas de hormonoterapia, integradas na prevenção terciária, como adjuvante de terapêuticas radicais, como paleação de doentes em recidiva bioquímica, ou no contexto de tratamento primário paliativo, apresentam vantagens e desvantagens que devem ser individualmente ponderadas. Resumo em inglês Aging is accompanied by progressive changes in hormones, cytokines and growth factors, some of them probably beneficial and others being associated with a higher risk of death by cardiovascular and oncological causes. Androgen replacement therapy in the elderly is becoming more frequent and is being used for longer periods, but the doubt remains regarding its impact in the risk of prostate cancer. Our experience from incident cases of prostate cancer shows that the propor (mais) tion of patients presenting worse prognostic factors for relapse or progression (higher basal PSA, risk of bone metastasis, tumours with worse histological differentiation grade) increases with age. While chemo-endocrine primary prevention waits for the results from ongoing studies (e.g. 5α-reductase inhibitors, selenium, vitamin E), secondary prevention, based on the partial results from large international studies and the expansion of measures for early diagnosis (digital rectal examination and PSA), takes the lead with the generalization of radical therapies. According to our 15-year experience of radical prostatectomy, the group of elderly patients (>65 years) represents half the subjects eligible for this treatment, has a higher proportion of subjects with a Gleason score ≥ 7 or classified in the groups of higher risk of recurrence or progression. The risks and benefits to be expected from the different forms of hormonotherapy, integrated in tertiary prevention, as adjuvant of radical therapies, as palliative in patients in biochemical relapse, or in the context of palliative primary treatment, need to be evaluated at an individual level.

Scientific Electronic Library Online (Portuguese)